A Low-Profile Wideband Filtering Transmitarray Antenna Using Multiresonance Patch Elements

This letter proposes a novel method of designing wideband low-profile filtering transmitarray (TA) antenna using multi-resonance patch elements. The TA unit integrates two sets of shared-aperture interleaved rectangular patches operating at different resonant frequencies. By properly tuning the multiple resonant frequencies of the patches, the design achieves bandwidth enhancement and high-order frequency selectivity with superior out-of-band suppression characteristics. A 3-bit transmission phase control mechanism is realized through a hybrid approach combining patch orientation reversal with dimensional parameter adjustments. The proposed high order filtering TA element has a compact three-metal-layer configuration on two stacked dielectric substrates, and the profile of the TA is as low as 0.1λ0, where λ₀ is the free space wavelength at the center of the operation frequency band. Based on the unit, a TA antenna is designed, fabricated, and measured. The measured peak gain and aperture efficiency are 26.5 dBi and 54.2%. The measured fractional 3-dB gain bandwidth is 24.2%. High suppressions of 33 dB and 31 dB are measured over the lower and upper out-of-bands. The advantages of the proposed TA include high-order bandpass filtering response, small thickness (0.1λ₀), broad operational bandwidth, high aperture efficiency, and cost-effective fabrication.